Accuracy of the WHO Haemoglobin Colour Scale for the diagnosis of anaemia in primary health-care settings in low-income countries: a systematic review and meta-analysis

Background Anaemia is a major cause of morbidity and mortality in low-income countries. Primary health-care workers in resource-poor settings usually diagnose anaemia clinically, but this is inaccurate. The WHO Haemoglobin Colour Scale (HCS) is a simple, cheap quantitative method to assess haemoglobin concentration outside of the laboratory. We systematically reviewed the literature to assess the accuracy of the HCS in primary care to diagnose anaemia, and compared this with clinical assessment. Methods We searched the electronic databases including MEDLINE, EMBASE, SCOPUS, Web of Science, Cochrane library, CINAHL plus, Popline, Reproductive Health Library, and Google Scholar and regional databases up to Nov 14, 2014, “haemoglobin colour scale” in alternative spellings published in any language. Two reviewers independently screened studies, extracted data, and assessed quality using the QUADAS-2 instrument. Statistical analyses were carried out in STATA using the bivariate model. Findings Of 141 records and abstracts screened, 14 studies were included. The pooled sensitivity of the HCS to diagnose anaemia was 80% (95% CI 68–88) compared with 52% for clinical assessment ([95% CI 36–67]; p=0·008). Specifi city was similar between the HCS (80% [95% CI 59–91]) and clinical assessment (75% [56–88]; p=0·8250). For severe anaemia, diagnostic accuracy was again higher overall for the HCS (p